1. Technical Field
The invention relates to an image projection method and an image projection apparatus. Particularly, the invention relates to an image projection method using a microelectromechanical system (MEMS) scanning mirror and a MEMS image projection apparatus.
2. Related Art
A microelectromechanical system (MEMS) generally refers to a research field that a microelectronics technique and a mechanical engineering technique are used to fabricate or develop related electronic components and mechanical structures, so as to miniaturize related products. Since a laser projection apparatus using a MEMS scanning mirror has effects of small size and low power consumption, etc., it is commonly used in smart phones or notebook computers, and becomes an indispensable part of portable audio and video apparatuses.
Generally, the MEMS scanning mirror is used to project an image light beam on a projection plane to provide an image. By controlling the MEMS scanning mirror to swing around different swing axes, the image light beam can scan back and forth on the projection plane along a corresponding direction. For example, if a scan frequency of the image light beam along a vertical direction of the projection plane is 60 Hz, when the MEMS scanning mirror swings around the corresponding swing axis, a swing frequency thereof is 60 Hz, and a control signal used for controlling the MEMS scanning mirror is generally a periodic wave signal which is 60 Hz, so as to present a required image quality.
However, the MEMS mirror itself also has a resonance frequency. Therefore, when the periodic wave signal is input to control the MEMS scanning mirror, the MEMS scanning mirror reacts with a harmonic component having the resonance frequency thereof in the periodic wave signal, and the image light beam may cause a problem of bright line on a projected image due to uneven swing speed of the MEMS scanning mirror during scanning. Therefore, it is an important issue concerned by related technicians to resolve the problem of bright line to provide better projection quality.